Background
Epidemiological studies have found that individuals who live in urban areas are at increased risk of developing psychosis. However it is unknown whether exposure to urban environments exacerbates psychotic symptoms in people who have a diagnosed psychotic disorder. The aim of the study was to examine the psychological and clinical effects of exposure to one specific deprived urban environment on individuals with persecutory delusions. It was predicted that the urban environment would affect emotional and reasoning processes highlighted in a cognitive model of persecutory delusions and would increase paranoia.
Method
Thirty patients with persecutory delusions were randomised to exposure to a deprived urban environment or to a brief mindfulness relaxation task. After exposure, assessments of symptoms, reasoning, and affective processes were taken. Thirty matched non-clinical participants also completed the study measures to enable interpretation of the test scores.
Results
In individuals with persecutory delusions, exposure to the urban environment, rather than participation in a mindfulness task, increased levels of anxiety, negative beliefs about others and jumping to conclusions. It also increased paranoia. The individuals with persecutory delusions scored significantly differently from the non-clinical group on all measures.
Conclusions
For individuals with psychosis, spending time in an urban environment makes them think more negatively about other people and increases anxiety and the jumping to conclusions reasoning bias. Their paranoia is also increased. A number of processes hypothesised in cognitive models to lead to paranoid thoughts are exacerbated by a deprived urban environment. Further research is needed to clarify which aspects of urban environments cause the negative effects. Methodological challenges in the research area are raised.
An impressively consistent literature now shows that the occurrence of psychosis is increased in urban environments (eg. Van Os, 2004, Sundquist et al., 2004, Marcelis et al., 1998 and Kirkbride et al., 2006). For example, in a longitudinal study of 4.4 million people in Sweden those people living in the most densely populated areas had 68–77% greater risk of developing psychosis than those in the least populated areas (Sundquist et al., 2004). However, less is known about whether exposure to urban environments increases psychotic symptoms in people who are already diagnosed with a psychotic illness. In examining this question, it is also possible to investigate the effects on cognitive and emotional processes resulting from environmental exposure, which might be involved in developing or exacerbating symptoms (Freeman, 2007 and Garety et al., 2007).
The aim of the study was, therefore, to investigate, for the first time, the effects of brief exposure to a specific urban environment on psychotic processes and symptoms. We hypothesised that entering an urban environment would lead to exacerbation of psychological processes implicated in a cognitive model of persecutory delusions (Freeman et al., 2002, Freeman, 2007 and Garety et al., 2001). That is, we predicted that spending time in a busy inner London high street would make an individual with current persecutory delusions more anxious, more negative about the self and others and increase the jumping to conclusions reasoning bias. Feeling more threatened, pessimistic and quick to make decisions would, in turn, be likely to increase paranoid thinking in a circular relationship. In this study, we did not set out to investigate which aspects, if any, of an urban environment, would be responsible for observed effects. The emphasis was on testing the effects of exposure to a real-life situation, routinely encountered by patients. This study of going into a busy street converges both with the traditional stress-vulnerability perspective on psychosis (eg. Zubin and Spring, 1977) and with recent research indicating that people with psychosis are especially emotionally reactive to everyday stress (see review by Myin-Germeys and van Os, 2007).
The clinical group predominantly contained individuals with a diagnosis of schizophrenia and an illness history of approximately ten years (see Table 2). On the PSYRATS, all clinical participants scored either 3 or 4 for delusion conviction and for delusion distress. These are the highest scores on the scale. For example, Category 3 is defined as conviction in the delusional belief as between 50–99% and Category 4 is defined as ‘conviction is 100%’. The participants were therefore experiencing strongly-held distressing persecutory delusions. It can be seen from Table 2 that randomisation had been successful.
